In Kieron Gillen's Darth Vader, Volume 1, there's a Star Wars character I'd not heard of before named Aphra who at one point says, "I'm happy my blood's doodling in the margins of a story worth telling" and therein lies my whole problem with this book. It's all the margins.
Set between A New Hope (i.e., episode 4) and The Empire Strikes Back (i.e., episode 5), the whole thing feels unnecessary. I'm never thrilled when yet another movie comes out set during one of the World Wars— haven't we heard all of the interesting stories by now?— so you can imagine how I'd feel about an unnecessary side story from a fictional war.
Of course, sometimes I'm still surprised, and someone will tell an interesting and new story. Even in the Star Wars mythos, I'll admit that my son and I enjoyed the Clone Wars TV series, which was set between Attack of the Clones (episode 2) and Revenge of the Sith (episode 3). So what I'm saying is, if the story telling is good enough, I can come around.
I didn't come around for Darth Vader, Volume 1. I'm left basically underwhelmed. It felt like just a way to squeeze out more Vader. I get he was a kick-ass villain and a money maker, but the character died and it's time to move on.
But, I'll concede some good points. For a guy who spends his entire time in a mask, they manage to get some emotion out of Vader— through his body language, through flashbacks, through words
— and I'll give credit for that. I'm not a fan of Larroca's art (especially his tendency to draw characters look straight into the "camera"), but Delgado's colours are great: dark, but shiny, just like Vader himself.